Staging Uveal Melanoma with Whole-Body Positron-Emission Tomography/Computed Tomography and Abdominal Ultrasound: Low Incidence of Metastatic Disease, High Incidence of Second Primary Cancers.

PURPOSE: The purpose of this study was to report the results of staging primary uveal melanoma with whole-body (18) fluorodeoxyglucose (FDG) positron-emission tomography/computed tomography (PET/CT) and abdominal ultrasound.

MATERIALS AND METHODS: From January 2012, patients with uveal melanoma over 4 mm in thickness were staged with FDG PET/CT and abdominal ultrasound.

RESULTS: Over 2 years, 108 patients with medium-to-large melanoma underwent dual imaging. According to the tumor, node, and metastasis classification, there were 75% T3, 11% T2, and 14% T1 uveal melanomas. Only, three of 108 patients (2.8%) were found to have metastatic uveal melanoma. All three had liver metastases confirmed following biopsy; one of three had additional extrahepatic widespread metastases. In these three patients, liver findings using both imaging techniques were consistent in one patient. In the second case, abdominal ultrasound missed the diagnosis of metastatic disease; however, FDG PET/CT revealed intense metabolic activity of the liver. In the third case, PET/CT missed the liver metastases; however, this was identified on abdominal ultrasound. PET/CT identified incidental second primary malignancies in 10 patients (9%). Second malignancies were found in the lung, breast, colon, thyroid, and adrenal gland. Abdominal ultrasound detected benign hepatic abnormalities in 20 patients (18%).

CONCLUSIONS: Whole-body PET/CT and abdominal ultrasound complement each other in the staging of uveal melanoma. Benign hepatic abnormalities found using ultrasound is common. Of importance, a second asymptomatic primary malignancy associated with uveal melanoma was detected almost one in 10 patients.